In various plants such as a gas turbine power plant, a nuclear power plant, a chemical plant, and an Integrated Gasification Combined Cycle (IGCC) plant, state quantities of the plant such as a temperature and a pressure are acquired in order to monitor whether or not the plant is normally operated.
For example, a heat exchanger which handles a generated carbon-containing fuel is provided in the IGCC plants. The heat exchanger performs heat exchange between the carbon-containing fuel (for example, fuel gas) and a heat exchange medium (for example, water) flowing through a heat transfer tube. However, since the carbon-containing fuel adheres to a heat transfer surface, an anomaly such as clogging of the heat transfer surface is likely to occur. Accordingly, the state of the heat exchanger which handles the carbon-containing fuel is also included in an object to be monitored to monitor whether or not the plant is normally operated.
Here, PTL 1 discloses a plant state monitoring method that monitors an operation state of a plant using a Mahalanobis distance based on a state quantity of the plant.
That is, in the plant state monitoring method disclosed in PTL 1, a first unit space preparation step and a second unit space preparation step are performed, in the first unit space preparation step, a first unit space, which is an aggregate of data becoming a reference when it is determined whether or not an operation state of the plant during a start-up operation period is normal, is prepared based on a state quantity during the start-up operation period of the plant, and in the second unit space preparation step, a second unit space, which is an aggregate of data becoming a reference when it is determined whether or not an operation state of the plant during a load operation period is normal, is prepared based on a state quantity of the plant during the load operation period.
In the first unit space preparation step, the first unit space is prepared based on the state quantity of the plant during a period from a time back to the past by a first period from a time when the state of the plant during the start-up operation of the plant is evaluated to a time back to the past by a second period from the same time. In addition, in the second unit space preparation step, the second unit space is prepared based on the state quantity of the plant during a period from a time back to the past by a third period from a time when the state of the plant during the load operation of the plant is evaluated to a time back to the past by a fourth period from the same time.